While you're in Texas - no, ASAP when you get to Texas - you have got to get out to Big Bend National Park in waaaaaaaaaaaaaaaaaaaaaaay west Texas. (Trace your finger down the Tex-Mex border from the western "point" to where you come to a big bend in the Rio Grande - that's it.)

The place is awesome. Was 35 years ago when I was a tyke, and 10 years ago when I, my wife, my son (then 10), my brother (then 14), and my sister (then 16) paddled about 100 miles on the Lower Canyons of the Rio Grande (ending our trip on the second of July -- talk about heat!). You are smack dab in the middle of the Chihuahua desert, but you can get up into the Chisos mountains in the center of the park where it is nice and cool (relatively).